For Two-wire ultrasonic level meter, its power supply (24VDC) and signal output ( 4-20mA ) share a loop, only two lines can be used, this is the standard transmitter form, the deficiency is that the transmission power is relatively slightly weak.
Three-wire ultrasonic level meter is actually four-wire system, its power supply (24VDC) and signal output (4-20mA) circuit separation, each of them use two lines, when they are connected to the negative end of the ground, usually use three lines. Its advantage is the large transmission power.
Post time: Jul-07-2022